Unless otherwise indicated herein, the description in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.
An image forming apparatus generally includes a paper feeder that houses a plurality of sheets. The paper feeder includes a feed roller and a retard roller. The feed roller sends out sheets from the paper feeder. The retard roller is in abutting contact with the feed roller to prevent multi feeding of the sheets.
The feed roller and the retard roller need to be replaced when a rotation count of the retard roller becomes equal to or less than a certain ratio with respect to the rotation count of the feed roller. This is because the sheets might not be conveyed due to a shortage of rotation of the retard roller even when multi feeding of the sheets does not occur. In other words, this is because a jam easily occurs. Reduction of the rotation count of the retard roller is mainly caused by an abrasion of the retard roller.
A replacement timing (a lifetime) of the retard roller can be determined by detection of the rotation count of the retard roller. For example, there is proposed a sheet conveyance apparatus that identifies which of a feed roller (a feed roller) and a separation roller (a retard roller) is deteriorated up to near its lifetime.
Specifically, the above-described sheet conveyance apparatus includes a Hall element, a velocity sensor, and a control unit. The control unit detects a cumulative rotation angle (a rotation count) of the separation roller per one paper feeding operation based on an output of the Hall element. The velocity sensor detects a moving velocity of the sheet sent out by the feed roller. The control unit determines which of the feed roller and the separation roller is deteriorated up to near its lifetime based on the cumulative rotation angle of the separation roller and detection results by the velocity sensor.